Bulletin of the American Physical Society
APS March Meeting 2023
Volume 68, Number 3
Las Vegas, Nevada (March 5-10)
Virtual (March 20-22); Time Zone: Pacific Time
Session S19: Superconductivity:CuO_& Nickelates |
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Sponsoring Units: DCMP Chair: Ajeesh Mukkattu Omanakuttan, Los Alamos National Lab Room: Room 211 |
Thursday, March 9, 2023 8:00AM - 8:12AM |
S19.00001: Tensor network simulations of electron-phonon coupling in the three band Hubbard model Nicole S Ticea, Thomas Devereaux, Luhang Yang, Hong-Chen Jiang It is believed that the CuO2 plane captures the essential features of high-Tc cuprates. To date, most numerical and analytical efforts towards understanding superconductivity in these materials has been via the effective one-band Hubbard model, which eliminates the oxygen degrees of freedom via the Zhang-Rice construction. This comes at the cost of modelling the undoped system as a Mott insulator instead of a charge-transfer insulator, thereby missing potentially important physics such as the role of oxygen p-bands as non-trivial hole carriers. Here we build upon prior Density-Matrix Renormalization Group (DMRG) and Quantum Monte Carlo (QMC) studies of the two-leg Three Band Hubbard (TBH) model by performing tensor network simulations of the TBH model with electron-phonon coupling. Various susceptibilities are measured towards the aim of clarifying the specific role of the copper dx2-y2 and oxygen px,y orbital degrees of freedom in mediating high-Tc superconductivity. Connections to the phase diagram of the cuprates are discussed. |
Thursday, March 9, 2023 8:12AM - 8:24AM |
S19.00002: Why Superconductivity Disappears in Very Overdoped La2-xSrxCuO4 John M Tranquada, Yangmu Li, Aashish Sapkota, Pedro Lozano, Barry Winn, Qiang Li, Genda Gu, Igor A Zaliznyak We have studied single crystals of La2-xSrxCuO4 with x = 0.25 and 0.29 [1]. Magnetization shows an onset of weak diamagnetism near 38 K, independent of field direction, and a transition to bulk shielding at 18 K (4 K), respectively, where the in-plane resistivity drops to zero. Inelastic neutron scattering measurements on the x = 0.25 sample reveal incommensurate magnetic excitations, similar to results at lower doping [2] but with reduced intensity, that develop a spin gap which, relative to a superconducting transition temperature of 18 K, is anomalously large. Sample characterizations demonstrate no evidence of phase separation. Instead, we argue that the random distribution of Sr dopants allows small regions of underdoped character to develop superconducting order at an elevated temperature, with bulk superconductivity occurring at a much lower temperature, limited by Josephson coupling between these self-organized grains, as proposed in [3]. The implication is that the locally-overdoped regions are not intrinsically superconducting. |
Thursday, March 9, 2023 8:24AM - 8:36AM |
S19.00003: Magnetotransport study of stripe-ordered La2−xSrxCu1−yFeyO4 Yuxin Wang, Bal K Pokharel, Dragana Popovic, Masaki Fujita, Takanori Taniguchi, Jun Sik Lee, Sang-Jun Lee In underdoped cuprates, some of the central issues are the interplay of charge and spin orders with superconductivity and their effect on the magnetic-field-revealed normal state. Recent magnetotransport studies of charge- and spin-stripe-ordered La2-xBaxCuO4 (LBCO) and La2-x-ySrx(Nd, Eu)yCuO4 (LNSCO and LESCO) near x=1/8 have revealed several intriguing properties of the high-field normal state. To investigate the universality of these novel properties and gain insight into their origin, we perform a similar study on stripe-ordered La2−xSrxCu1−yFeyO4 (LSCFO), which has a crystal structure (low-temperature orthorhombic) that is different from that of LBCO, LNSCO, and LESCO (low-temperature tetragonal). Magnetotransport measurements were done on samples with hole doping 0.10 ≤ p ≤ 0.15 in perpendicular fields up to 41.5 T and at temperatures 0.02 ≤ T (K) ≤ 300. The results allow us to construct the (T, H) phase diagrams, explore the properties of the high-field normal states, and study their dependence on doping. |
Thursday, March 9, 2023 8:36AM - 8:48AM |
S19.00004: Interplay of Lattice and Charge Density Waves in Cuprates Jiahao Yan, Zengyi Du, Hui Li, Seamus Davis, Kazuhiro Fujita A now famous charge density wave (CDW) state emerges with moderate hole doping into CuO2 layer of cuprates. To describe the CDW state, two different pictures on two sides of electron-phonon coupling strength are proposed. In the weak coupling limit, the CDW state occurs when Fermi surface are scattered by the phonon with the same wavevector Q. While in the strong coupling case, larger lattice distortion amplitude maximally separates the strong interacting charges in real-space which is also indicated by the prominent broadening width of the Kohn anomaly around the same wavevector Q. Hence, in the simplest case of 1-dimensional state, one might expect Q = p for a strong coupling CDW and Q ∝1 - p for a weak coupling CDW. However, in hole-dope Bi2Sr2CaCu2O8 when p «1, the dependence of Q(p) observed remains constant until the CDW state disappears at p ≥ 0.2. We attempt to explore the issue by combining lattice displacement and CDW imaging. |
Thursday, March 9, 2023 8:48AM - 9:00AM |
S19.00005: Photoinduced behavior of charge density wave in YBa2Cu3O6.67 : Bridging the gap between equilibrium and nonequilibrium normal states in high-Tc cuprates Hoyoung Jang, Sanghoon Song, Takumi Kihara, Yijin Liu, Sang-Jun Lee, Sang-Youn Park, Minseok Kim, Hyeong-Do Kim, Giacomo Coslovich, Suguru Nakata, Yuya Kubota, Ichiro Inoue, Kenji Tamasaku, Makina Yabashi, Heemin Lee, Changyong Song, Hiroyuki Nojiri, Bernhard Keimer, Chi-Chang Kao, Jun-Sik Lee In cuprate superconductors, charge density wave (CDW) has been ubiquitously observed, particularly by X-ray scattering technique, and investigated as an important aspect in normal state. To study the normal state of the cuprates at low temperature below Tc, the superconductivity has been suppressed by applying either an external magnetic field or an optical pump laser. Those excitations respectively induce equilibrium or nonequilibrium normal state. The development of high intense, ultrashort pulsed X-ray sources, i.e. X-ray free electron lasers, opens another chapter of the CDW studies, e.g. discovery of three-dimensional (3D) CDW and characterization of transient behaviors. In this talk, we present the transient behavior of CDW in YBa2Cu3O6.67. We utilized 800 nm (1.55 eV) optical laser pump and Cu L3-edge (932 eV) X-ray probe for time-resolved resonant elastic soft X-ray scattering. Below Tc, the suppression of superconductivity enhances CDW intensities within a few ps. We further observed out-of-plane correlation changes, which resemble field-induced 3D precursor correlation. Ultimately, we discuss that a transient normal state triggered by the laser-driven quench of the superconducting state is possible to represent phenomena of the equilibrium state. |
Thursday, March 9, 2023 9:00AM - 9:12AM |
S19.00006: Direct observation of vortices in infinite-layer nickelate superconductors Ruby A Shi, Kyuho Lee, Bai Yang Wang, Yusuke Iguchi, Harold Hwang, Kathryn A Moler We use a scanning SQUID (Superconducting QUantum Interference Device) to study local magnetic properties of an infinite-layer nickelate Nd0.85Sr0.15NiO2 thin film grown on LSAT ((LaAlO3)0.3(Sr2TaAlO6)0.7) substrate, and a Nd0.775Sr0.225NiO2 thin film grown on SrTiO3. We find a reduced number of magnetic inclusions for nickelates grown on LSAT, in contrast to the ferromagnetic background caused by NiOx nano-particles in nickelate films grown on SrTiO3. The reduced ferromagnetic background allows us to see superconducting vortices by imaging their magnetic field a few micrometers above the sample. The extrapolated Pearl length from fitting vortices (~ 400 um at 3 K) agrees with local susceptibility measurements. This Pearl length translates to a 1.1 um in-plane penetration depth for a thin film of 7 nm. Our study confirms the improved sample quality of nickelates grown on LSAT, and to our knowledge, is the first to reveal superconducting vortices in this recently discovered superconductor. |
Thursday, March 9, 2023 9:12AM - 9:24AM |
S19.00007: Materials Synthesis Approaches to Infinite-Layer Nickelate Thin Films from a High-Crystallinity Precursor Phase Danfeng Li, Zhengang Dong, Marios Hadjimichael, Bernat Mundet, Jean-Marc Triscone Zhengang Dong1, Marios Hadjimichael2, Bernat Mundet2, Jean-Marc Triscone2, Danfeng Li1 |
Thursday, March 9, 2023 9:24AM - 9:36AM |
S19.00008: Effect of Stoichiometry and Strain on the Stabilization of Infinite-Layer Nickelates Kyuho Lee, Bai Yang Wang, Yonghun Lee, Berit H Goodge, Woojin Kim, Lena F Kourkoutis, Harold Hwang Following the discovery of superconductivity in infinite-layer nickelates,1 the degree to which these nickelates can be considered an analog material for the unconventional cuprate superconductors remains an important question. While notable experimental distinctions – for example, in the ground state of the non-superconducting regions of the superconducting phase diagram – have been made, whether these distinctions are intrinsically tied to the multi-band nature of the nickelates or extrinsically driven by crystallinity limitations has remained unclear.2-4 In this context, significant improvement in the materials control of these thermodynamically unstable infinite-layer nickelates is of utmost importance. Following the recent breakthrough in the crystallinity of Nd1–xSrxNiO2 (x = 0.05-0.325) thin films,5 we discuss the detailed optimization of the two-step stabilization of this material. In particular, we reveal how two key factors – cation stoichiometry and epitaxial strain – significantly influence the crystallinity and the resultant transport properties of these infinite-layer nickelates. Systematic structural and transport characterizations of these infinite-layer nickelate thin films will also be discussed in detail. |
Thursday, March 9, 2023 9:36AM - 9:48AM |
S19.00009: Characterizing the Bond-Percolation Metal-Insulator Transition in La1-xRxNiO3 Nickelates (R = Nd, Sm) Angel A Martinez, Gregorio Ponti, Leodan Villegas-Avina, John T Markert We report x-ray diffraction, electrical resistivity, and scanning electron microscopy measurements on improved-purity, bulk polycrystalline La1-xRxNiO3 (R = Nd, Sm; x = 0–1) materials to further test the prediction of a universal T –> 0 Metal-Insulator (M-I) transition for all (La,R)NiO3 nearly-cubic-perovskite materials. The samples were prepared using a sol-gel nitrate precursor, facilitating reduced grain sizes, a key factor in procuring pure specimens. Samples were then reacted under high oxygen pressure (100-200 bar), high temperature (750°C-1050°C) conditions, with various cooling rates. Phase purity was improved over our previous study[1]; the new data provide some unity and contrast with those prior results, and with that study's bond-percolation model, in which the M-I transition occurs at a (universal) small R concentration of only xc = 0.294..., which corresponds to the fraction of non-conducting bonds at the percolation threshold on a simple cubic lattice, (1– pc) = 0.751... |
Thursday, March 9, 2023 9:48AM - 10:00AM |
S19.00010: Inelastic neutron scattering study of the infinite layer nickelate Nd0.8Sr0.2NiO2 Stephan Rosenkranz, Daniel Phelan, Bixia Wang, Hong Zheng, Douglas L Abernathy, Antia S Botana, John F Mitchell Infinite layer nickelates with spin-1/2 Ni1+ ions in square coordination in NiO2 planes exhibit similar electronic properties as the cuprates. The observation of superconductivity up to 15K in thin films of the infinite layer nickelates thus opened the question whether superconductivity in these compounds has the same underlying pairing mechanism as the cuprates. While much theoretical and experimental efforts have been devoted to these systems, the difficulty to synthesize infinite layer compounds in particular in bulk form, leaves many open questions regarding their properties, Here we report inelastic neutron scattering investigations performed on a bulk sample of Nd0.8Sr0.2NiO2, the same nominal composition for which superconductivity was observed in thin film form grown on a SrTiO3 substrate. These measurements provide the phonon density of states, which can give provide insight on possible superconducting mechanisms, and provides direct information regarding the Nd3+ crystal field states. |
Thursday, March 9, 2023 10:00AM - 10:12AM |
S19.00011: Nernst effect and thermopower in an infinite-layer nickelate superconductor Nicholas P Quirk, Bai Yang Wang, Kyuho Lee, Danfeng Li, Harold Hwang, N. Phuan Ong The diffusion of superconducting vortices generates a Josephson electric field that can be probed in transport experiments (vortex Nernst effect). Famously, large vortex Nernst signals have been recorded in the high-Tc cuprate superconductors at temperatures well above the loss of the Meissner effect (flux expulsion) [1]. The discovery of superconductivity in the infinite-layer nickelates, (A,Sr)NiO2 (A=La, Pr, Nd) [2], has drawn many comparisons to the cuprates. We discuss careful measurements of the vortex Nernst effect and thermopower in the precursor regime of superconducting Nd1-xSrxNiO2 thin films. |
Thursday, March 9, 2023 10:12AM - 10:24AM |
S19.00012: Rare-earth Dependence of the Superfluid Density in Nickelates Bai Yang Wang, Shannon Harvey, Jennifer Fowlie, Motoki Osada, Kyuho Lee, Yonghun Lee, Danfeng Li, Harold Hwang Infinite-layer nickelates present a new family of strongly correlated superconductors [1-3]. Some key open questions include the superconducting gap symmetry and their potential dependence on the rare-earth elements [4,5]. Here we present our characterization of the superfluid density in (R,Sr)NiO2 (R = La, Pr, Nd) utilizing the mutual inductance measurement technique [5]. For La and Pr-nickelates, the superfluid density shows a quadratic temperature dependence, indicating nodal superconducting gap structure in the presence of disorder. Nd-nickelate instead exhibits complex low-temperature behavior due to the magnetic contribution of the Nd3+ 4f moments [6]. These results are consistent with the unconventional nature of superconductivity in the nickelates. |
Thursday, March 9, 2023 10:24AM - 10:36AM |
S19.00013: Electronic character of charge order in square planar low valence nickelates Yao Shen, Jennifer Sears, Gilberto Fabbris, Jiemin Li, Jonathan Pelliciari, Matteo Mitrano, Wei He, Junjie Zhang, John F Mitchell, Valentina Bisogni, Michael R Norman, Steven S Johnston, Mark P Dean Charge order is a central feature of the physics of cuprate superconductors and is known to arise from a modulation of holes with primarily oxygen character. Low-valence nickelate superconductors of mixed charge-transfer–Mott-Hubbard character [1] also host charge order, but the electronic character of this symmetry breaking is unsettled. Here, using resonant inelastic x-ray scattering at the Ni L2-edge, we identify intertwined involvements of Ni 3dx2−y2 , 3d3z2−r2 , and O 2pσ orbitals in the formation of diagonal charge order in an overdoped low-valence nickelate La4Ni3O8. The Ni 3dx2−y2 orbitals, strongly hybridized with planar O 2pσ, largely shape the spatial charge distribution and lead to Ni site-centered charge order. The 3d3z2−r2 orbitals play a small, but non-negligible role in the charge order as they hybridize with the rare-earth 5d orbitals. Our results reveal that the low-energy physics and ground-state character of these nickelates are more complex than those in cuprates. |
Thursday, March 9, 2023 10:36AM - 10:48AM |
S19.00014: Competing stripe phases in the undoped infinite-layer nickelate Ruiqi Zhang, Christopher A Lane, Johannes S Nokelainen, Bahadur Singh, Bernardo Barbiellini, Robert S Markiewicz, Arun Bansil, Jianwei Sun Recent discovery of superconductivity in the nickelates has ignited renewed theoretical and experimental interest in the role of electronic correlations in their properties. In this talk, based on in-depth first-principles and random phase approximation modeling, I will show that the parent (undoped) compound of the nickelate family, LaNiO2, hosts competing low energy phases, unlike the undoped cuprates but similar to the case of the doped cuprates. In particular, we find charge density wave vectors in agreement with experimental findings. We also show that flat bands near the Fermi level, stemming from the Ni-3dz2 orbitals, persist across the various predicted low-energy phases of the nickelates. Our study gives insight into the microscopic origin of electronic inhomogeneity and the lack of long-range order in nickelates. |
Thursday, March 9, 2023 10:48AM - 11:00AM |
S19.00015: Critical spin nature of the Cooper pairing of Nickelate superconductors: resembling cuprates, Moiré magic-angle graphene, and heavy-fermion UTe2? Lin Er Chow, Shengwei Zeng, Saurav Prakash, Zhaoyang Luo, King Yau Yip, mathieu pierre, Zhaoting Zhang, Tobias Heil, Julia Deuschle, Proloy Nandi, Sujith Kunniniyil Sudheesh, Zhi Shiuh Lim, M. Nardone, Abdelaziz Zitouni, Peter A van Aken, Elbert Chia, michel goiran, Swee Kuan Goh, walter Escoffier, Ariando Ariando One of the ideal routes to unravel the high-Tc pairing mechanism in cuprates is through a ‘twin sister’ – a cuprate analogue, which mimics the electronic and structural templates. Standing beside copper in the periodic table, Ni1+ in the infinite-layer phase hosts a 3d9 electronic structure - resembles the Cu2+ state in cuprates. Following the two decades debates, the recent experimental data suggests both significant similarities and distinctions to the high-Tc cuprates [1-5]. Surprisingly, some of these distinctions marked a close resemblance to the magic-angle Moiré multilayer graphene and heavy-fermion spin-triplet superconductor UTe2. Particularly, we revealed a large Pauli-limit violation in all crystallographic directions, which suggests that nickelates may host both spin-singlet and spin-triplet pairing mechanisms. In this presentation, we will share our recent angular-dependent magnetotransport and spectroscopy data, and discuss the hidden connections between nickelate superconductor and the strongly-correlated cuprates, Moiré multilayer graphene, and spin-triplet UTe2. |
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